10mm glass end for water pipe attachment!The VapCap is unlike any other vaporizer, so give it a few tries empty to get the feel of its unique temperature-indicating click. Heat the VapCap in a quiet area, listen and feel so you know what you are looking for. If you are using a torch lighter, this should not take more than 5 or 6 seconds. Heat the middle of the cap not the end and rotate while heating. If more than 6 seconds go by and you don’t hear the click, stop heating and let it cool down.